Advances in angiography have enabled radiologists to position catheters within virtually any branch of the splanchnic arterial tree. These techniques have permitted diagnosis of vascular syndromes causing gastrointestinal bleeding as well as gastrointestinal ischemia. Utilizing these techniques, a number of investigators have reported clinical application of vasoconstrictors in the management of gastrointestinal hemorrhage and vasodilators in the management of gastrointestinal ischemia. The bulk of the evidence which has resulted in this clinical application is derived from feline and canine experimentation. Recent evidence indicates, however, that the subhuman primate responds to instillation of pharmacologic agents in his splanchnic circulation in a manner which differs from observations in dogs. Although "autoregulatory escape" may be demonstrated in canine and feline experimentation, the same may not be true of the subhuman primate and, therefore, presumably man as well. In addition, recent evidence indicates that while the endogenous catecholamines are vasoconstrictors in the splanchnic circulations of carnivores, epinephrine is a vasodilator depending upon the dose and route of administration in the gut of the subhuman primate. Needed now is a comprehensive investigation to determine the action of the effects of vasoactive agents in the separate splanchnic circulations of the subhuman primate in an effort to more clearly predict the role of these agents in regulating the splanchnic circulation of man. It would be possible to predict with more precise evidence theoretical effects of these agents in man. This information should enable a more scientific approach to the salvage of patients considered to be poor operative risks but with ischemic or hemorrhagic lesions of the gut amenable to pharmacologic intervention and possible correction of the disease process.